(please Alexander, is this setup too dry ?). Let me say the skimmer is not noisy and made of good materials.

As Alexander said in one thread, once you have left the skimmer run at least one day with the water outlet completely open and also the air intake (the skimmer coming with a silencer but no air valve or airline clamp is provided),
I've closed the air with a silicon hose and the air tap (fully open) from my old Deltec Skimmer in order to get a consistent foam.

Than I begun to close the output valve slowly bringing the border line you can see between the water and the bubble when they start to form foam to around 10 cm (range between 5 (wet) and 10 cm (dry)) under the cup connector.
I started to have a good skimate after minutes